The present invention relates to toothbrushes and, in particular, it concerns a toothbrush with longitudinal to lateral motion conversion.
It is known that best results are achieved by brushing teeth with an upwards and downwards action, thereby helping to remove food material stuck in the cracks between adjacent teeth. In practice, however, only a small proportion of users actually take the trouble to perform such a brushing action. Instead, most users revert to the much easier, but less effective, side-to-side brushing action.
In power-driven toothbrushes, this problem is commonly addressed by causing vibration or rotation of brush elements perpendicular to the handle (which is generally parallel to the side-to-side primary direction of motion). Examples of power-driven toothbrushes which employ such an action may be found in U.S. Pat. No. 2,583,886 to Schlegel, U.S. Pat. No. 2,665,675 to Grover, and U.S. Pat. No. 5,864,911 to Arnoux et al.
In the field of manual toothbrushes, however, the problem is not so readily solved. A wide variety of toothbrush structures have been proposed in an attempt to produce a secondary up-down motion even when the user only actively moves the toothbrush in a side-to-side primary direction of motion. Many of these employ rotatable bristle-carrying elements deployed so as to rotate about an axis perpendicular to the primary direction of motion. Examples of such structures may be found in U.S. Pat. No. 5,142,724 to Park, U.S. Pat. No. 5,186,627 to Amit et al., and U.S. Pat. No. 5,996,157 to Smith et al. None of these, however, has been found particularly effective.
An alternative solution is suggested in U.S. Pat. No. 1,643,217 to Lazarus. Here, a spiral arrangement of bristles extends along a rotatable shaft rotatably mounted parallel to the primary direction of motion. The description states that “the spiral arrangement of the bristle tufts tends to cause the bristle member, when rubbed against the teeth or the like to rotate on the handle and so to bring a fresh surface continually into use.” In practice, however, since the axis of rotation is parallel to the direction of motion, it is clear that little or no rotation would actually be induced.
In an unrelated field of endeavor, U.S. Pat. No. 4,438,601 to Olson discloses a sandpaper cleaning device in which two rollers with brushes are set at an oblique angle to the handle. Because of the angle of the rollers, longitudinal motion of the device causes rotation of the rollers which, in turn, induces sideways “skidding” of the brushes across the sandpaper. A similar principle is used in various agricultural equipment. This concept has not, however, heretofore been used in the field of toothbrushes.
There is therefore a need for a manual toothbrush which would effectively produce a secondary up-down motion when the user only actively moves the toothbrush in a side-to-side primary direction of motion. It would also be highly advantageous to provide a method for brushing along a row of teeth so as to generate a brushing action perpendicular to a direction of motion.